The difference between the compositions according to the invention and conventional polymerizable compositions based on unsaturated polyesters is that the polymerizable groups to be derived from the .alpha., .beta.-unsaturated carboxylic acid is not part of a polymeric chain, but instead is a lateral group of such a chain.
The advantage of the process is that it is possible to produce polymerizable compositions of this kind very simply, quickly and sparingly in a one-pot reaction without any need to apply drastic temperature conditions and without any need to use solvents.
Another advantage lies in the considerable range of variation of the process. It enables the properties of the polymerizable compositions and the properties of the polymerization products which are produced from them to be varied within wide limits in terms of functionality and degree of crosslinking. In addition, the wide range of vinyl monomers, but especially the wide range of compounds to be used as .alpha., .beta.-unsaturated carboxylic acids, coupled with the possibility of using other carboxylic acids, provides for further variation in the properties of the end products.